1. Field of the Invention
The present invention relates to the preparation of fluorobenzonitriles, and, more espcially, to the preparation of fluorobenzonitriles from their corresponding chlorobenzonitriles by reaction of the latter with an alkali metal fluoride.
2. Description of the Prior Art
It is known to this art to prepare fluorobenzonitriles by the reaction of chlorobenzonitriles with an alkali metal fluoride, such as potassium fluoride, in aprotic solvents, such as, for example, dimethylformamide, dimethylsulfone and sulfone (see, for example, British patent specification No. 2,016,000), optionally in the presence of a catalyst, such as cesium fluoride (see French Pat. No. 2,391,990).
Yet the known reactions proceed far too slowly to be of significant value on an industrial scale.